In order to use or access any of these, you have to buy them with BP from the Rewards Menu in Extras. Be warned: using the infinite rocket launcher/bowgun/etc will result in a C ranking for the stage as well as reduced BP.

Unlockable	How to unlock
Chicago Typewriter	Beat all four episodes.
Classic Horror Filter	Beat all four episodes on Casual with an S-rank.
Comic Noir Filter	Beat all four episodes on Survival with an S-rank.
Countdown Mode	Beat all four episodes.
Cursed Video Filter	Beat all four episodes on No Escape with an S-rank.
Infinite Ammo for all weapons	Beat all four episodes on No Escape difficulty.
Infinite Bowgun	Beat all four episodes.
Infinite Rocket Launcher	Beat all four episodes under three hours.
Invisible Mode	Beat all four episodes.
Meat Grinder	Beat all four episodes on Survival.
Moira's Katana	Beat all four episodes in Invisible Mode.
Natalia's Bubble	Beat all four episodes in Countdown Mode.
No Escape Difficulty	Beat all four episodes on Survival difficulty.
RE1 Barry Costume	Beat all four episodes.
RE2 Claire Costume	Beat all four episodes.
Sepia-Toned Filter	Beat all four episodes on Normal with an S-rank.
Short Sword	Beat all four episodes on Normal.
Sniper Claire Costume	Beat all four episodes and get the "good" ending.